Cross shaft universal joint: Essential Components In The Car

Cross shaft universal joint is one of the most commonly used couplings. Using the characteristics of its structure can make the two shafts that are not on the same axis or have larger axis fold angles or larger axial movements rotate at a constant angular speed, and reliably transmit torque and motion. It can be widely used to transmit torque in the mechanical shafting of metallurgy, lifting, engineering transportation, mining, petroleum, shipping, coal, rubber, paper machinery and other heavy machinery industries.

Classification of cross shaft universal joint

Cross shaft universal joint can be divided into single cross shaft and double cross shaft.

Single cross shaft universal joint transmission, the transmission shaft is enclosed in a sleeve that transmits traction or braking force from the drive axle to the frame or body. However, its structure is bulky and increases the weight of the non-suspended part. Moreover, since only one cross shaft universal joint transmission is used in this structure, it is not guaranteed that the rotation speeds of the drive shaft of the main reducer and the second shaft of the transmission are constant, which causes uneven work. This kind of universal joint application is very less.

The most widely used at present is the double cross shaft universal joint. The double cross shaft universal joint is directly connected with two simple cross shaft universal joints and a transmission shaft. In addition, the double cross shaft universal joint is light in weight, because this universal joint has a simple and compact structure, high strength, good durability, high transmission efficiency, and low production cost. It can make it not coaxial or have a large axis angle. The two shafts with large movement continuously rotate at a constant angular speed and are matched with a telescopic transmission shaft. The universal shaft with a cross shaft is widely used.

characteristics of the cross shaft universal joint

The characteristics of the cross shaft universal joint one: the structure is compact and reasonable, the structural design of the cross shaft universal shaft is very rigorous and compact, so the carrying capacity of the cross shaft universal coupling is very strong, and it is safe and reliable .

The second characteristic of the cross shaft universal joint: the cross shaft type universal shaft has a large carrying capacity. The torque it can transmit is relatively large, so the universal shaft coupling of the cross shaft is more prominent in the range of matching equipment for mechanical equipment with a limited diameter of rotation.

The characteristics of the universal joint of the cross shaft are three: the energy-saving characteristics of the universal joint of the cross shaft are significant, because the traditional efficiency of the universal joint is high, which can generally reach 98%, so that it can be improved in work. Work efficiency, thereby achieving the effect of energy saving.

The characteristics of the cross shaft universal joint are four: the cross shaft universal coupling has low noise and smooth operation. In the production process, the noise of the mechanical equipment is also a performance of low efficiency, and it is not beneficial to the use of the mechanical equipment itself, and the noise of the universal joint of the cross shaft is very low, and its operation is relatively stable, which can make the work More efficient completion.

The selection of the cross universal joint shaft is very important to us, because if there is no good choice, it will affect the use of the universal joint shaft, so it needs to be taken seriously. When choosing a cross universal axis, the following aspects should be considered:

1. Torque size, nature and shock absorption requirements, such as high power and heavy load transmission, gear coupling can be used.

2. The rotation speed of the universal joint shaft and the centrifugal force it generates. If it is a high-speed transmission shaft, you should choose a coupling with high balance accuracy instead of a slider coupling.

3. The relative displacement between the two axes of the universal axis. After installation and adjustment, if the relative displacement is large, the elastic coupling should be used.

4. Safety and reliability of the universal joint shaft and working environment. Generally speaking, if the coupling does not require lubrication, it is relatively reliable; if lubrication is required, its performance will be affected by the lubrication conditions, and there may be other problems.

The cause of the failure of the cross shaft universal joint

Here are some reasons why the cross shaft type universal shaft fails, so that everyone can deal with it calmly and can take some effective measures to solve this problem.

Reason one: oblique imprint

When the total circumferential clearance of the bearing in the cross shaft type universal shaft is relatively large, the needle roller is prone to skew, so that a certain angle of embossing occurs between the journal and the axis of the cross shaft. If the imprint continues to go deeper, it will make the needle roller unable to rotate and increase the frictional resistance. Therefore, the total circumferential clearance of the bearing should be controlled within the range of 0.1-0.4mm.

Reason two: fatigue spalling

If the radial gap between the cross shaft and the bearing gradually expands due to wear, the load will be concentrated, and the fatigue indentation will occur at the place where the load is relatively large, and eventually fatigue spalling will occur, and it will be large in area.

Reason three: lack of oil and ablation

If the lubrication is not in place or the lubrication is insufficient, or the bearing seal is not good, it will cause oil loss in the bearing, or aging and cracks in the sealing material. In addition, if there is no lubricating oil, the temperature of the cross shaft universal shaft will be too high during use, causing the bearing and the journal to seize, damage the needle roller and sealing parts, etc., and eventually the surface of the ring Ablation occurs.

Reason four: the needle or shim fails

If there are pits, pits on the surface of the needle, or the needle head is broken, the needle will fail. The failure of the gasket is mainly due to the fracture of the gasket or the wear of the gasket. These are all related to the size structure of bearings and gaskets, so they must be designed reasonably. In addition, the material of the gasket should be selected with relatively high strength and wear resistance to avoid this phenomenon.

Maintenance of cross shaft universal joint

1) Check

Checking whether the cross universal joint shaft is abnormal during operation can not only ensure safety, but also improve the operation rate of mechanical equipment, which is also beneficial to prolong the service life of the universal coupling. If any abnormality is found, the operation should be stopped immediately to find out the cause.

2) Lubrication

Regular lubrication of bearings and splines. In addition to the operation, oil should be injected once a week within six months. Once the working conditions are stable, oil should be injected once every six months, while the spline shaft and the universal coupling used for the main drive of the rolling mill should be oil injected once every three months.

3) Maintenance

When abnormal sound, vibration, oil leakage and other abnormal phenomena are found, the machine should be shut down as soon as possible for decomposition and inspection. Even if no abnormality is found, periodic inspections should be carried out, especially the cross universal joint shaft used in important parts and long-term continuous use that cannot be stopped in the middle, and they must be regularly repaired. The standard time is 5000 hours or one year, and the specific time should be determined according to the conditions of use.

4) Disassembly

When disassembling, the dirt and oil on the cross universal joint shaft should be removed, and foreign objects should be prevented from entering the bearings and splines. Before disassembling, use white paint to mark the joints, bearings, cross shafts and other parts to prevent misalignment during assembly.

5) cleaning

Bearings and cross shafts cannot be cleaned in the same oil sump where other parts are cleaned, and compressed air should be used to dry them after cleaning.

6) Check

After disassembly, the main parts should be carefully inspected for wear and damage and replaced according to their extent. Check the cross shaft and rolling surface for peeling, pitting, abrasion, and indentation. If such damage is found, replace it.

7) Assembly

When assembling, proceed in the reverse order of disassembly, and press the white mark to make it exactly the same position as before disassembly. The phase of the prongs on both ends of the spline shaft and the spline sleeve must be the same; ensure the axial clearance of 0.05~0.10mm on one side of the cross shaft; the coupling bolts should be pre-tightened with a torque wrench according to the specified pre-tightening torque; Relubricate its bearings and splines.

Application of cross shaft universal joint in automobile

1) Universal joint transmission device from automobile transmission to drive axle;

2) Universal joint transmission between the transmission on the allwheel drive and the transfer case and between the transfer case and the front and rear drive axles Moving device;

3) Universal joint transmission device between clutch and transmission of heavy vehicle;

4) Universal joint transmission device used in drive axle with swinging half shaft;

5) The universal joint transmission of the steering axle of the car.

In addition to the above, some special vehicles, such as off-road vehicles, agricultural vehicles, dump truck winches, power output devices and to meet the needs of the steering wheel and steering gear layout, most of them use cross universal joint transmission devices.

Cross shaft universal joint in automobile is a key component of automobile transmission shaft. Cars are moving objects. On the rear-drive vehicle, the engine, clutch and transmission are mounted on the frame as a whole, and the drive axle is connected to the frame through an elastic suspension. There is a distance between the two and they need to be connected.

1. Function:

cross universal joint in automobile is generally composed of cross shaft, cross bearing and flange fork. The universal joint is a key component of the automobile transmission shaft. On vehicles driven by the front wheels of the engine, the universal joint drive shaft is installed between the transmission output shaft and the input shaft of the drive axle main reducer; while vehicles driven by the front wheels of the engine omits the transmission shaft, the universal joint is installed on the half shaft between. The front axle and wheels responsible for driving and steering. The angle and distance between the output shaft of the transmission and the input shaft of the final drive of the transaxle will change due to road bounce, load changes, or the difference in the installation positions of the two assemblies. Therefore, a "variable strain" device is needed to solve this problem, so a universal joint is produced.

2. Transmission characteristics:

In cars equipped with front and rear wheel drive (or all-wheel drive) engines, due to suspension deformation during movement, there is often relative movement between the input shaft of the main drive reducer and the output shaft of the transmission (or gearbox). In addition, in order to effectively avoid certain mechanisms or devices (which cannot achieve linear transmission), a device is needed to realize the normal transmission of power. The universal joint drive appears. The universal joint transmission must have the following characteristics:

A). Ensure that the relative position of the two connected shafts can reliably transmit power when the predicted range changes.

B). Ensure that the connected two axes run evenly. The additional load, vibration and noise caused by the angle of the universal joint should be within the allowable range.

C) . High transmission efficiency, long service life, simple structure, easy manufacturing and maintenance. For automobiles, since the output shaft of the cross shaft universal joint rotates unevenly with respect to the input shaft (at a certain angle), it must be driven by a double universal joint (or multiple universal joints), and two universal joints connected to the drive shaft The pitch fork is arranged on the same plane, and its angle is equal to the two universal joints. This is important. When designing, the angle between the universal joints should be minimized.